agree with this
There is no good way to test your team besides actually testing your team in the map you want to know if it'll work
Do i want a practice map with some basic monsters and a few strong ones with no cost? YES
Should there be any? NO
Bare with me on this one, if you can 3* and actually farm every map on the first try, you will never grow desperate, if you never grow desperate then you wont consider spending SC on refilling CHA and or STA, if you don't use SC to refill them then you keep stocking on them, if you have a lot you never have the need to buy them, if you don't buy them they don't gain money
i say this from personal experience, on Ada's event i couldn't 2* that G map, let alone farm it, so i spent 50 SC on a rush to get a good tank in order to be able to complete it; i'm not proud of this, but i cannot be the only one
it is a stretch, yes, but they effectively lose money if one can just be certain how their units will develop under certain circumstances
Also i really like going blind for the first tries, usually i can do it on the 3rd try but if i can't THEN i go to video guides, that way i can develop a formation of my own while still having fun and have a plan B so i don't go crazy trying the same map dozens of times